Electronic device including a channel layer including gallium nitride
An electronic device can transistor having a channel layer that includes a compound semiconductor material. In an embodiment, the channel layer overlies a semiconductor layer that includes a carrier barrier region and a carrier accumulation region. The charge barrier region can help to reduce the likelihood that de-trapped carriers from the channel layer will enter the charge barrier region, and the charge accumulation region can help to repel carriers in the channel layer away from the charge barrier layer. In another embodiment, a barrier layer overlies the channel layer. Embodiments described herein may help to produce lower dynamic on-resistance, lower leakage current, another beneficial effect, or any combination thereof.
1. An electronic device comprising:
a substrate;
a carrier accumulation layer overlying the substrate;
a carrier barrier layer overlying the carrier accumulation layer; and
a channel layer of a transistor overlying the carrier barrier layer, wherein the channel layer includes a compound semiconductor material comprising GaN and has a thickness in a range of 50 nm to 550 nm,
wherein the carrier accumulations layer, the carrier barrier layer, or each of the carrier accumulation layer and the carrier barrier layer includes Al x Ga (1−x) N, wherein x is in a range of 0.01 to 0.49, and
wherein the carrier accumulations layer has a higher concentration or donors or acceptors as compared to the carrier barrier layer.
2. The electronic device of claim 1 , wherein each of the carrier accumulation layer and the carrier barrier layer includes Al x Ga (1−x) N, wherein x is in a range of 0.08 to 0.12, and the carrier accumulation has a greater concentration of a carrier impurity as compared to the carrier barrier layer.
3. The electronic device of claim 1 , wherein:
the carrier accumulation layer has a first bandgap energy;
the carrier barrier layer has a second bandgap energy;
the channel layer has a third bandgap energy; and
the second bandgap energy is greater than the third bandgap energy.
4. The electronic device of claim 3 , wherein the second bandgap energy is greater than the first bandgap energy.
5. The electronic device of claim 4 , wherein the carrier accumulation layer includes GaN and has a thickness no greater than 900 nm.
6. The electronic device of claim 1 , wherein the carrier barrier layer is at least 1.5 times thicker than the carrier accumulation layer.
7. The electronic device of claim 1 , further comprising a barrier layer overlying the channel layer.
8. The electronic device of claim 7 , wherein each of the carrier accumulation layer, the carrier barrier layer, the channel layer, and the barrier layer includes a III-N material.
9. The electronic device of claim 8 , further comprising a gate electrode of the transistor, wherein the gate electrode is spaced apart from the channel layer by the barrier layer.
10. The electronic device of claim 1 , wherein the transistor at 150° C. has a resistance reduction that is given by:
(( R DSON-max −R DSON-VDS )/( R DSON-max ))*100%,
wherein R DSON-max is a maximum on-state resistance a drain-to-source voltage is in a range of 0 to 700 V, and R DSON-VDS is an on-state resistance at a particular drain-to-source voltage (V DS ); and
wherein:
when V DS is 300 V, the resistance reduction is at least 2%;
when V DS is 400 V, the resistance reduction is at least 3%;
when V DS is 500 V, the resistance reduction is at least 6%;
when V DS is 600 V, the resistance reduction is at least 6%; or
any combination thereof.
11. The electronic device of claim 10 , wherein:
when V DS is 300 V, the resistance reduction is no greater than 10%;
when V DS is 400 V, the resistance reduction is no greater than 20%;
when V DS is 500 V, the resistance reduction is no greater than 35%;
when V DS is 600 V, the resistance reduction is no greater than 35%; or
any combination thereof.
12. The electronic device of claim 1 , further comprising:
a barrier layer overlying the channel layer;
a gate electrode of the transistor, wherein the barrier layer is disposed between the channel layer and the gate electrode;
a source electrode of the transistor; and
a drain electrode of the transistor,
wherein:
the carrier barrier layer abuts each of the carrier accumulation layer and the channel layer;
the carrier accumulation layer includes Al x Ga (1−x) N, wherein x is in a range of 0.08 to 0.12, has a concentration of a carrier impurity of a first carrier type that is at least 1×10 18 atoms/cm 3 , and has a thickness in a range of 200 nm to 300 nm;
the carrier barrier layer includes Al x Ga (1−x) N, wherein x is in a range of 0.08 to 0.12, has a concentration of a carrier impurity of the first carrier type that is no greater than 3×10 16 atoms/cm 3 , and has a thickness in a range of 600 nm to 900 nm;
the channel layer includes GaN, has a concentration of a carrier impurity of the first carrier type that is no greater than 3×10 16 atoms/cm 3 , and has a thickness in a range of 110 nm to 300 nm; and
the barrier layer includes Al x Ga (1−x) N, wherein x is in a range of 0.15 to 0.30, and has a thickness in a range of 5 nm to 40 nm.
13. An electronic device comprising:
a substrate;
a carrier accumulation region overlying the substrate;
a carrier barrier layer overlying the carrier accumulation layer; and
a channel layer of a transistor overlying the carrier barrier layer, wherein the channel layer includes GaN,
wherein each of the carrier accumulation layer and the carrier barrier layer includes Al x Ga (1−x) N, wherein x is in a range of 0.08 to 0.12.
14. The electronic device of claim 13 , wherein the carrier accumulation layer is at least 1.5 times thicker than the carrier barrier layer.
15. The electronic device of claim 13 , wherein the channel region includes GaN.
16. The electronic device of claim 15 , further comprising a barrier layer that includes Al x Ga (1−x) N, wherein x is in a range of 0.15 to 0.30.
17. The electronic device of claim 1 , wherein the channel layer comprises carbon as a dopant.
18. The electronic device of claim 1 , further comprising a superlattice structure comprising Al z Ga (1−z) N, where 0≦z≦1.
19. The electronic device of claim 18 , wherein the superlattice structure overlies the substrate and, in the superlattice structure, an Al content decreases and a Ga content increases as a distance from the substrate increases.
20. The electronic device of claim 19 , wherein a nucleation layer is disposed between the superlattice structure and the substrate.